Cone Traits Research Articles

Geographical variation in cone traits of Pinus nigra as result of crossbill predation: implications for assisted migration

The interaction between Spanish Black pine (Pinus nigra subsp. salzmannii) and common crossbill (Loxia curvirostra) could have resulted in a geographic mosaic of coevolution in the Iberian Peninsula. In turn, this coevolutionary interaction might limit the future applicability of assisted migration as a tool to adapt forests of Spanish Black pine to ongoing climate change. Several cone and seed traits were measured in 740 cones collected at six stands distributed across the range of Spanish Black pine. Data were analysed by means of linear-mixed effects models, canonical analysis of principal coordinates and random-forest analysis. Results showed that cones from the northern pine populations exhibited more defensive traits against crossbill predation than cones from the central and southern populations, resulting in a geographic mosaic of selection. Assisted migration of P. nigra would involve moving southern populations toward the north of the species’ range and would result in introducing the genotypes of pines with poorly defended cones into areas where crossbills are comparatively more abundant. The resulting risks for the regeneration prospects of the translocated trees are discussed.

Cone quality and seed efficiency in the clones from mutational witches brooms ofPinus sibirica

Mutational witches' broom is a fragment of the tree crown with abnormal morphogenesis including slow shoot growth, abundant branching and decreased apical dominance which caused by somatic mutation that presumably originates in the apical meristem bud. To study the variability in the cone quality and seed efficiency in witches' broom clones ofPinus sibirica, the cone size and structure were assessed in 21 mutant clones. The mutant clones were significantly differentiated both by the cone traits and seed quality. Their cone size varied from less than 3 to 4 cm. The clones had large number of sterile scales in proximal and distal cone parts, and from 16 to 39 fertile scales per cone. Cones from all mutant clones were inferior to average normal cones of the species. Six clones had large portion of filled seeds, more than 70%, and the other clones had less than 50% of filled seeds. The clones had 10-33% of empty seeds and 1-73% of seeds with collapsed megagametophyte per cone. In general, the seed quality in mutants was quite low, but individual clones had almost normal seed quality, and their seed efficiency was within the species norm.

Aleppo Pine Seed Production of Several Tunisian Ecotypes Planted in a Coastal Forest Stand

The demand of Aleppo pine seeds has risen largely to reach the Mediterranean countries necessities in the last decades. To study seed cone production of the species, 33 blocs (12x10m; 120m2) were planted with a limited number of Tunisian Aleppo pine ecotypes where only twelve are selected here to be surveyed. During plantations all ecotypes are spaced two meter each other. Selected ecotypes are evaluated for their survival rates, measured for their epidometric variables (total height (Ho) and their diameter at breast height (DBH)). Therefore, the average tree characteristic for each ecotype is defined as a representing tree and then an overall of 40 trees were used for cones harvesting. Consequently, seed and cone production variability between Aleppo pine ecotypes is detected using simple regression analysis. Results showed an overall survival rate of 82.9% within the site since 1963. High significant (p<0.01) linear positive relationship (Ho-DBH was recorded across ecotypes. Ecotypes variability is noticed for all the measured parameters including seed cone production parameters. However, coastal forest Aleppo pine stand showed an overall produced seed cone number less than the half (50 Cones/tree) in comparison to non-coastal forest within Tunisia. Similarly, in the coastal forest, the produced cones size and weight are often smaller and have less seeds contents than those produced within non-coastal forests. Likewise, we thought that cone traits are a major factor influencing seed yield in coastal forest stands. Finally, obtained results can be used as a scientific support to reach futures investigations research work in others Aleppo pine planted zones in Tunisia.

Interannual variability of germination and cone/seed morphometric characteristics in the endemic Grecian fir (Abies cephalonica) over an 8-year-long study

AbstractAbies cephalonicacone and seed morphometric characteristics as well as seed germination behaviour were investigated during an 8-year-long diachronic study (2007–2015). The research was carried out in Parnitha National Park, in the part of this Greek endemic, silver fir population that was spared from an unprecedented wildfire (2007). A statistically significant interannual and among-tree variation of cone traits has been identified, except for cone diameter. Cone length is correlated to the number of seeds per cone, while the percentage of empty seeds has been consistently high, with extreme values of 29.3 and 81.8% in a masting (2015) and lean crop (2009) year, respectively. There is also a considerable proportion of dead (including infected) and non-germinated seeds, and the eventual germinable fraction is well below 25% with spikes in masting years (39.4 and 60.9% in 2010 and 2015, respectively). Untreated seeds have been tested at a wide range of constant and alternating temperatures and germination is completed within 4–5 weeks atT≥ 15°C andca15 weeks at 5–10°C. A chilling pretreatment of 4–8 weeks (at 2–4°C) concludes germination at 15–20°C within 2 weeks. A significant white light requirement has been observed for untreated seeds at 15–20°C, while germination was light indifferent at lower or higher temperatures. Data obtained in this study confirm the present, field seed germination during springtime; we may also predict an earlier germination (late autumn to mid-winter) in forest gaps, under the predicted, warmer conditions in the future.

Variation in needle and cone traits in natural populations of Pinus yunnanensis

Pinus yunnanensis Franch. is a major component of coniferous forests in southwestern China. Little is known about its intraspecific variation. Morphological variations in needle and cone traits of P. yunnanensis were analyzed to quantify variability among and within natural populations. Seven traits were measured on 10 needles collected from 30 trees in each of the 18 sampled populations of P. yunnanensis. Four cone traits were measured in 221 individual trees from nine populations. The results showed that there were significant differences (p < 0.01) both among populations and within populations in each needle and cone trait. The proportion of phenotypic variation of nearly all needle and cone traits was over 50 % within populations, which showed trees within populations accounted for a majority of the total variation. The needle traits showed higher variability within population than cone traits. Variability in the needle traits was correlated with geo-climatic parameters (longitude, latitude, altitude, temperature, and precipitation). Needle length and the ratio of needle length to fascicle sheath length showed clinal variation in response to latitudinal and altitudinal gradients. A hierarchical classification of all populations based on needle traits led to the formation of four major groups. The findings provide important genetic information for the evaluation of variation. Moreover, it will assist in management of genetic diversity of P. yunnanensis.

Anatomical differences between Pinus mugs Truro populations from the Tarts Mts.. expressed in needle traits and in needle and cone traits together

Two-year-old needles were collected from 429 individuals of dwarf mountain pine (&lt;em&gt;Pius mugn&lt;/em&gt; Turra) from 10 populations of this species growing in the Tatra Mts. (5 populations from calcareous and 5 from calcium-free undersoil). Thirteen anatomical traits of the needles were studied. For obtaining a full picture of the variability of the dwarf mountain pine, the differences were investigated in ten populations (385 plants) as regards 27 traits of needles and cones. The data obtained by measurements served as basis for performing multivariate analysis of variance and testing the statistical hypotheses, for discriminant analysis, calculation of the Mahalanobis distances and construction of a minimum spanning tree of the shortest Mahalanobis distances and agglumerative clustering by the method of' nearest neighbourhood. The results of these analyses indicated that the dwarf mountain pine populations differ ,statistically significantly as regards the whole complex of needle traits and form three groups not correlated with the type of undersoil on which they grow. Most closely similar are the populations from Kominy Tylkowe, Morskie Oko and Wyżni Toporowy Staw. The population from Kobylarz is the most diverse. Investigation of' the differences in the complex of' needle and cone traits proved that the traits of cones are decisive for the variability picture.

Variability of eight Polish populations of Pinus sylvestris L. expressed in traits of cones

Two-year old cones were collected from 257 standing &lt;i&gt;Pinus sylvestris&lt;/i&gt; L. trees, representing 8 Polish populations of the species. The cones were analyzed in respect to 11 morphological traits. The obtained data were subjected to multivariate statistical analysis to determine interpopulation variability. Multivariate analysis of variance was performed with testing of statistical hypothesis, Mahalanobis distances for each pair of populations were calculated and their significance was estimated using Hotelling T2 statistics. Using the shortest Mahalanobis distances a dendrite was constructed while Euklidean distances provided grounds for hierarchy grouping. Most of the populations were found to differ significantly from the remaining ones. The population from Ruciane proved to be most distinct. Cone setting angle was the trait of the highest discriminating power in interpopulational comparisons. Using the Bryant's test, the discussed populations were found to form two geographic groups: the north-eastern population group and the south-western one.

Morphological differences between Pinus mugo Turra populations from the Tatra Mts. revealed by cone traits

Two-year-old cones were collected from 388 dwarf mountain pine (&lt;em&gt;Pinus mugo&lt;/em&gt; Turra) plants of ten populations of this species from the Tatra Mts. - five of them from calcareous and five from calcium-free undersoil. Their 14 morphological traits are described. The data served for performing multivariate analysis of variance and testing of statistical hypotheses, for discriminate analysis. for calculating Mahalanobis distances between populations and plotting a dendrite based on the shortest Mahalanobis distances and for agglomerative clustering by the method of nearest neighbourhood. Wide differences in the populations were found as regards all the studied traits and the existence of two groups in the population, which, do not, however, correlate with the substrate type. The "calcareous and calcium-free" populations show statistically significant differences in six of the 14 studied traits.

Intrapopulational variability of Pinus sylvestris L. from Piekielna Góra in respect to cone and needle traits

From 37 Scots pine trees in Piekielna Góra the two-year old cones were collected and studied in respect to 14 morphological traits including the setting angle. One-year old cones from the same trees were examined in respect to their setting angle only. The data obtained for two-year old cones were subject to a whole range of multivariate analytical methods, to detect variability between randomly selected trees. Discriminant analysis was performed, Mahalanobis distances between each pair of trees were calculated and their significance was estimated using the Hotelling T&lt;sup&gt;2&lt;/sup&gt; statistics. A minimum spanning tree was constructed on the basis of the shortest Mahalanobis distances while Euklidean distances served to perform cluster analysis. The randomly selected sample of Scots pine population did not show any internal, significantly differentiated groups and variability among the trees was low. Cone dimensions belonged to the most variable traits, but the ratio of cone length to cone width showed the lowest variability. The extensive similarity of the population to the other earlier examined populations of &lt;i&gt;Pinus sylvestris&lt;/i&gt; L. from the Kłodzko District, and certain divergencies from the population are demonstrated.

Variation in cone and seed characters in blue pine (Pinus wallichiana) across natural distribution in western Himalayas

We analyzed 17 seed sources (seed stands) of Pinus wallichiana for variations present in cone and seed characters, scattered over natural distribution in north-west Himalayan states (Uttarakhand and Himachal Pradesh) of India. The significant variations were observed in cone weight, cone length, cone width, seed length, seed width, seed weight, seed germination, radicle length, and plumule length among different seed sources of the species. Significant positive correlation between seed weight, cone weight and cone width showed that seed weight in the species depend more on the cone size. Seed germination was also positively correlated with seed weight, cone weight and radicle length in the study. The estimates of variability with regard to genetic parameters for seed weight, seed germination, cone length, cone width, cone weight showed wide range of variation in the study. Seed weight showed high heritability values coupled with maximum genetic gain. Traits with such values indicate presence of good amount of heritable additive components and are under strong genetic control. The findings of the study revealed that seed sources expressed both phenotypic and genotypic differences in the seed and cone traits which might be due to the differences in genetic make up of various seed sources and environmental factors i.e. genotypic and environmental interaction. The study suggests that the seed weight should be given the top priority for the further improvement of this species.

Great spotted woodpeckers Dendrocopos major exert multiple forms of phenotypic selection on Scots pine Pinus sylvestris

Relatively few animal species extract seeds from closed conifer cones because of the forces required to spread apart or penetrate the woody scales. Those species that forage on seeds in closed cones tend to forage selectively, and therefore act as selective agents on cone structure. However, little is known about the foraging preferences and thus phenotypic selection that is exerted on conifers by many species that forage extensively on seeds in closed cones, including especially woodpeckers (Picidae). Great spotted woodpeckers Dendrocopos major are one of the main predators of seeds in closed cones of Scots pine Pinus sylvestris in central and eastern Europe. To estimate the cone preferences of these woodpeckers foraging on Scots pine, we contrasted traits of cones that were and were not foraged on by woodpeckers. Woodpeckers preferred to forage on shorter cones when scales were thin (smaller apophyses) but preferred cones of intermediate length when scales were thicker, providing evidence for correlational selection. The preference for intermediate-sized cones indicates that woodpeckers exert disruptive selection on cone length when cones have thicker scales, but the overall selection on cone length across all scale types indicates directional favoring the evolution of longer cones. Woodpeckers avoided cones with thicker scales, which would lead to directional selection favoring the evolution of thicker scales. Preferences for intermediate-sized cones have been found in tree squirrels and directional selection favoring the evolution of cones with thicker scales may be a common outcome of the foraging behavior of birds.

Low levels of population genetic structure in Pinus contorta (Pinaceae) across a geographic mosaic of co‐evolution

Population genetic analyses provide information on the population context in which evolutionary processes operate and are important for understanding the evolution of geographically variable traits. Earlier studies showed that cone structure of lodgepole pine in the Rocky Mountains diverged among populations because of geographic variation in coevolutionary interactions involving mammalian and avian seed predators. Analyses of population genetic variation are needed to determine whether this divergence has arisen despite extensive gene flow and whether populations to the east and west of the Rocky Mountains have evolved convergent phenotypes independently. We investigated genetic structuring across 22 stands of lodgepole pine in the central Rocky Mountains and in isolated peripheral populations that experience different seed predators and exhibit parallel divergence in cone traits using a set of nine simple sequence repeats and 235 AFLP loci. Our analyses reveal high levels of genetic diversity within and low genetic differentiation among populations. Nonetheless, geographic and genetic distances were correlated, and isolated populations to the east and west of the Rocky Mountains had higher levels of differentiation than did populations in the central part of the range. These data indicate not only that adaptive divergence of cone traits across a geographic mosaic of coevolution has occurred despite minimal genetic differentiation, but also that isolated populations to the east and west of the Rocky Mountains have evolved distinctive cones independently and in parallel. The population structure quantified here will inform future research aimed at detecting genetic variants associated with divergent adaptive traits.

Variability of the traits of cones and seeds in different larch clones: I. The influence of the provenance.

Phenotypic variability of the cones and seeds was studied on seven larch clones that were obtained through grafting from plus trees, selected from natural and artificial populations from Romania. Also, correlations between several characteristics such as cones weight (g), cone length and width (cm), seed weight (mg), seed length and width (mm) were studied. A wide variation was observed for the weight of cones, ranged between 1.97-4.93 g, the average for all clones being 3.50 g. The coefficient of variability for cones weight oscillated, depending on the provenance, from 11.1% to 21.2%. Seeds weight varied between 54.4-74.4 mg, with a mean value of 61.9 mg. The weight of cones was positive correlated with all traits, except width of cones and seeds length. Weight of seeds was strong correlated with all traits, the biggest value of the coefficient of correlation being registered with the weight of cones (0.835). A very strong correlation (+0.939) was registered between the germination energy and germination capacity of seeds, but germination of seeds was negative linked with all traits of cones and seeds, not statistically correlated. The heritability in broad sense had high values, comprised between 0.943 (width of cones) and 0.993 (weight of cones). The results had illustrated that the peculiarities of the cones and seeds have a strong genetic determinism, influenced especially by the genotype and in a relatively small extent by the environment.

Habitat area and structure affect the impact of seed predators and the potential for coevolutionary arms races

Both habitat patch size and structure affect the abundance and occurrence of species and thereby can affect the ecology and evolution of species interactions. Here we contrast the level of seed predation and selection exerted by Common Crossbills (Loxia curvirostra complex) and red squirrels (Sciurus vulgaris) in the extensive mountain pine (Pinus uncinata) forests in the Pyrenees with their level of seed predation in two small, isolated forests. Crossbills consumed 5.1 times more seeds in the Pyrenees than in the isolated forests, and six of seven cone traits under selection by crossbills were enhanced in the Pyrenees. In contrast, red squirrels tend to be uncommon in the open mountain pine forests, consuming relatively few seeds in both regions and having limited impact on both mountain pine and the interaction between crossbills and mountain pine. Resident crossbills in mountain pine forests in the Pyrenees have larger bills than in nearby forests, consistent with local adaptation by crossbills and a coevolutionary arms race between crossbills and mountain pine. The mechanisms leading to variation in the interaction between crossbills and mountain pine should be general to many systems because habitat patch size and structure often vary across the range of a species.

Morphometric traits and sexual dimorphisms do not strongly differentiate populations of Zeravshan juniper ( Juniperus seravschanica Kom.) in Kyrgyzstan

Intra- and among-population variations of Juniperus seravschanica were morphologically examined in eight populations originating from elevations of 1300–2200 m a.s.l. in Kyrgyzstan. Eleven traits of needles and cones were studied on 70 vouchers. In addition, height, diameter, stem form, and sex of 172 trees were recorded in the field in order to test whether male trees invest more in vegetative growth than females and if sex ratio is shaped by (limited) environmental resources. Morphological differences among populations were small, but needle length, width and thickness were statistically different. However, differences based on needle traits were independent from geographical, altitudinal and environmental distances. In sharp contrast to studies in other Juniperus species, sex ratio in J. seravschanica was strongly female biased (3.5 females : 1 male). Moreover, no correlation between the habitat conditions and the sex ratio was detected, suggesting that within the altitudinal range of this species, females occur more frequently. This has implications for sustainable use and the conservation of J. seravschanica populations. It is likely, that due to the higher investment of male individuals in vegetative growth males are more exploited than females. An average effective population size of 70% of the respective census suggests that conservation measures and non-selective logging regimes are required to allow reproduction and a natural regeneration of this species.

Chloroplast diversity in a putative hybrid swarm of Ponderosae (Pinaceae)

The Ponderosae subsection of the genus Pinus contains numerous taxa in disjunct mountain ranges of southern Arizona and New Mexico, differing for several leaf and cone traits, key among which is the number of leaf needles per fascicle. Trees with three needles are often found together with trees having five needles and mixed numbers. One taxonomic hypothesis is that there are swarms of hybrids between P. ponderosa and P. arizonica. A second hypothesis is that there are spatial mixtures of two separate taxa, five-needle P. arizonica and a "taxon X" containing three needle and mixed needle trees. We genotyped chloroplasts in one putative hybrid swarm on Mt. Lemmon using microsatellite markers and show that cpDNA is almost completely differentiated between two separate morphotypes corresponding to P. arizonica and "taxon X." Little if any introgression has occurred on Mt. Lemmon, and the simplest explanation is that little or no effective hybridization has occurred. Further results indicate that not only is taxon X not of hybrid origin, it is more closely related to nonregional Ponderosae other than P. ponderosa and P. arizonica. The results further suggest that other putative hybrid swarms in the region are also spatial mixtures of distinct taxa.

Adaptive radiation through phenological shift: the importance of the temporal niche in species diversification

Abstract1. Phenological shift in oviposition in seed predators may be a key factor for adaptive radiation if temporal differences lead to less intense competition.2. This hypothesis was tested at two sites in the French Alps in three sympatric species of larch cone flies grouped into two phenological groups (early and late) differing in adult emergence and oviposition timing by approximately 2 weeks. The present study assessed the intensity of competition within and between groups by measuring four larval traits. Cone traits were measured, and the impact of early species parasitism on cone development was assessed.3. The occupation of the central axis of a developing cone by one early larva has a strong detrimental effect on cone growth and seed production. However, there was almost no correlation between the variables measured on the cones and on the larvae, suggesting that the resources available were not limiting.4. Inter‐group competition had no significant effect on early larvae. In contrast, both inter‐ and intra‐group competition had a significant negative effect on late larvae length (–11% and –16% respectively), dry mass (–8% and –23%), and lipid mass (–15% and –26%). The intensity of competition was stronger among larvae in the same phenological group, which is consistent with the hypothesis that shifts in oviposition promote adaptive radiation in larch cone flies by reducing competition among larvae.

Intra-stand variation of cone structure and seed production in Siberian stone pine: pattern and use for breeding

Siberian stone pine (Pinus sibirica Du Tour) in Russia is primarily valued as a nut-bearing species. Therefore, intra-stand variation in its cone structure and seed production have been actively studied during the last 50 years. However, these studies are poorly related to practical breeding. We used a novel system of traits to characterize yearly seed crops at the different levels of its structural organization. The purpose is to analyze the results of long-term observations of the intra-stand variation of the reproductive features complex, and to reveal the pattern and character of its diversity. This information would be useful to develop the method of searching the initial material for breeding. The research plot is established in the Nizhne-Sechenovo forest located 25 km from Tomsk in the south part of the boreal zone (170 years old, mean height 22 m, mean d.b.h. 60 cm). The number of sampled trees varied between 40-120 among years. The registration of seed crop and analysis of its structure was conducted every year from 1990 to 2005. The intra-stand variation of the traits' level was determined as a standard deviation in percent from the simple average. The level of variability rose sharply and the correlations between them decreased in the years of the low crops. The results concerning variation in seed and cone traits are listed in the next table. The number of full seeds depended rather on losses in the processes of development (r = 0.80*-0.85*) than on their starting number (r =0.55*-0.60*). The mass of one seed with sound endosperm rose with an increase in the ratio of the ovules, which were lost at the earlier stages of development (r = 0.20-0.25*) and the flat seed ratio (r = 0.35*-0.40*). In year-to-year dynamics, the number of cones per tree is positively connected with the number of filled seeds per cone (r = 0.78*) and with other indices characterizing 'the crop quality'.The breeding rank of trees by all important traits remains relatively stable from year to year. Consequently, even in the years of big crops even the most productive trees fully use its potential. A considerable increase in seed production by means of artificial selection of the best genotypes is therefore possible without a visible decrease in the crop quality and without intensification of the cone-bearing irregularity. Criteria and method of selection of the initial material for the Siberian stone pine breeding as nut-bearing species have been suggested.

Demographics, pollination syndrome and conservation status of Macrozamia platyrhachis (Zamiaceae), a geographically restricted Queensland cycad

To assess the International Union for Conservation of Nature (IUCN) status of Macrozamia platyrhachis F.M.Bailey, we surveyed this central Queensland cycad for its population abundance and health and its pollinator type and pollination syndrome (thermogenesis and volatile emissions). Plants are locally abundant within the 11 discrete populations surveyed, with an estimated population of 611 315 adult plants. Plants are highly restricted to a small area of occupancy, seed dispersal is nearly non-existent and extreme fires appear to have destroyed almost all seeds and seedlings and decimated the pollinators. Of known Macrozamia pollinators, only the thrips, Cycadothrips chadwicki Mound, were found on cones, and these were found in very low numbers. The pollination syndrome for this cycad appears to be unique, based on two cone traits. For one, thermogenesis peaks in early evening, a contrast with daytime peaks of other Cycadothrips-pollinated Macrozamia, but matches that of the Tranes weevil-pollinated Macrozamia machinii. In addition, cone volatiles include both previously unreported compounds as well as those reported exclusively on either Cycadothrips- or Tranes-pollinated species. Based on its small, fragmented area of occupancy, projected population declines and the unique pollination syndrome, we recommend that M. platyrhachis retain its current status as ‘Endangered’. Habitat management plans should stipulate that controlled burns be avoided during cycad coning season and that wildfires be controlled to minimise damage to seedlings and pollinators.

Selection by a predispersal seed predator constrains the evolution of avian seed dispersal in pines

SummaryPrevious studies have demonstrated that wind dispersal is an effective mode of seed dispersal for pines (Pinus, Pinaceae) with seeds weighing &lt;90 mg, but not for larger‐seeded (≥90 mg) pines. Consequently, most large‐seeded pines rely on birds in the family Corvidae for seed dispersal, but some do not, and most of their seeds fall near the parent tree. Why seeds of these pines are not dispersed by corvids, and have not evolved traits that facilitate seed dispersal by corvids, is enigmatic.One factor that may constrain the evolution of seed dispersal by corvids in pines, or in other plants that rely on birds for seed dispersal, is predispersal seed predation. The most important predispersal seed predators of pines are often tree squirrels in the generaTamiasciurusandSciurus, which have repeatedly been shown to drive the evolution of seed defences in conifers.We first use published data showing how selection on cone traits of two bird‐dispersed pines by tree squirrels (Tamiasciurus) favouring increased seed defences, conflicts with selection by a corvid (Nucifraga columbianaWilson) for cone traits that facilitate seed dispersal, to make predictions about changes in cone and seed structure of large‐seeded pines that should evolve in response to selection by either tree squirrels or corvids.The cone and seed structures from several other large‐seeded pines in regions with and without pine squirrels were consistent with these predicted changes. Consequently, large‐seeded pines that co‐occur withTamiasciurusor other tree squirrels are well defended against both squirrels and corvids, and instead probably rely on other animals, such as ground‐foraging rodents, that disperse fallen seeds (secondary seed dispersal). Only where tree squirrels are uncommon or absent are conifers likely to evolve traits that enhance seed harvest by corvids in large‐seeded pines.